Established in 1984 by account managers Dominic Wheatley and Mark Strachan, whose given names derived the company name. The two worked in an advertising agency, where computers attracted their attention when they hatched a plan to attract a new corporate client- it was Commodore. They approached Commodore with the idea of bundling an adventure game with each of their computers, with the game having the added attraction of a £25,000 prize for the first person to solve the game. Presumably Commodore declined the offer, but Wheatley and Strachan forged ahead regardless. Domark solicited the services of fantasy author Ian Livingstone and released their first game in 1984- a text adventure for the C64 and Spectrum called EUREKA!. A £25,000 prize was offered to anyone who could solve the adventure before the end of 1985. The promotion proved successful and the prize was won by UK teenager Matthew Woodley.

Domark made the most of their small yet enterprising beginnings and published games for the next decade on all the major 8- and 16-bit formats. In 1995, Eidos Interactive was formed when Eidos plc acquired Domark, Simis and Big Red Software as a means to launch itself into the entertainment software market. In 1996, with the success of the Sony PlayStation imminent, Eidos plc acquired CentreGold plc (which included US Gold, Core Design and Centresoft). Despite massive growth in the late 90s, Eidos Interactive admitted in March 2005 that its cash reserves had dwindled to £11.9m during the second half of 2004 and pre-tax losses had grown to £29m. That same month, Eidos received a takeover bid from British games manufacturer SCi Entertainment. The takeover was finalised on 16 May 2005. Since the SCi takeover, the vast majority of the old Eidos management have been forced out.